The electronic structures, atomic geometries, formation energies, and ionization energies of substitutional Al and B in the cubic material were calculated by using the first-principles pseudopotential method. It was shown, by calculations of the ionization energies, that both Al and B formed a shallow acceptor level on a Si site, and a deep level on a C site. In the case of Al, a Si site required a lower formation energy than did a C site; regardless of the composition. In the case of B, the lower formation-energy site depended upon the composition. The C site was favorable for B under Si-rich conditions, while a Si site was favorable under C-rich conditions. The results suggested that low-resistivity p-type crystals could be prepared under C-rich conditions when B was used as a dopant.

A.Fukumoto: Physical Review B, 1996, 53[8], 4458-61